The overall objective of the proposed research is to combine a genetic and biochemical approach to analyze the expression of a tissue specific gene product in a eucaryote. We will investigate the mechanisms of gene regulation during spermatogenesis in the free-living nematode Caenorhabditis elegans by first identifying, isolating and characterizing sperm-specific proteins. Mutants and naturally occurring populations of C. elegans will be screened for quantitative or qualitative changes in sperm proteins. Mutants and naturally occurring variants exhibiting alterations in sperm proteins will be analyzed to determine the genetic and biochemical basis of tissue specific gene expression. Antibodies will be prepared against different sperm proteins and used as in situ probes to determine when and where particular sperm proteins are synthesized in wild type and mutant worms. We will select mRNAs coding for different sperm proteins and make cDNA. This cDNA will be used for the construction of recombinant DNA molecules containing DNA sequences known to be transcriptionally active during spermatogenesis. These cloned cDNAs will be used as in situ and in vitro probes to derermine when and where the RNA transcripts for sperm proteins are synthesized in mutant and wild type worms and to determine the nature of the primary transcript.